# Why is the map projection question too opinion based?

There is a recent Map Projection question:

Which map projection would result in an accurate visual depiction of a mega crater?

It seems quite clear to me, how does the asker map a large physical shape on a spherical world onto a 2 dimensional map with minimum distortion.

But it's been closed as "Too Opinion Based".

I don't want to just mod hammer it open as I may well have missed something but I'd be interested to see a wider opinion on whether it should be open or closed or an explanation of what I missed...

• Thanks for raising this. I was considering if I should have raised a meta question about closure, even though I got an accepted answer. Though to be honest, the accepted answer didn't actually answer the question so much as point me somewhere where I can figure it out for myself! – EveryBitHelps Oct 5 '16 at 16:25
• Thanks to whoever moved the question off 'on hold'! – EveryBitHelps Oct 5 '16 at 21:00
• Obligatory xkcd reference – JDługosz Oct 7 '16 at 11:41

## 2 Answers

Map projections are not opinion based, each has specific advantages depending what it is you need to display accurately. The best answer to a question like this can be shown mathematically to be the one that gives the least distortion.

• But how do you quantify distortion? At some point it becomes a question of opinion about which metric is best, or which gives better-looking results. – 2012rcampion Oct 13 '16 at 23:20
• @2012rcampion, in this case he's asked to minimise visual distortion of the crater itself. The mathematics of map projections mean there isn't one "best" overall projection, only a best projection for the specific task at hand. For a circular feature like this I'd recommend an azimuthal projection co-centered on the feature, but it's not really my specialist subject. – Separatrix Oct 14 '16 at 7:25

While I don't agree with the closing because as I see the point of asking/answering is to get as answers that are as factually information based as possible with moderate deviation to account for different knowledge bases and lines of thought. This includes a small bit of opinion.

In this case, all map projections have various levels of distortions at different points, or usefullness. We can quantify the type and how much distortion there is in any given area of a map projection and as a result can say that x projections at y point have the least amount of distortion. And then we have to factor in, which of those are best suited to the intention of the question, which is an opinion. Is my answer with using an equirectanglular projection the best answer or is a Dymaxion projection the best answer? Dymaxion maps have the least distortion, but noone uses them because they're not really all that useful. And that's the case with many projections. They're made up by someone that just wanted to prove a point or fairly crazy, but no one uses them, because, while yes, they are maps, they're not very practical to use.

Using this reasoning, there is practically an infinite number of answers based on the opinion aspect of the question. Yet again, however, we come to a cut off point generated by the common "reasonable expectation". The normal person doesn't know of or want a Dymaxion map or any of those other insane maps that noone uses and taking this implication into account it quickly limits the question to rectangular or near rectangular maps that are used by most map makers and there we can establish the best map to use for the effect and remove the opinion.

Or in the case of what I did, provide a tool or information to the limits of the question so that the asker fill in their own opinions to finish the answer to the question.

So while I agree there is opinion involved it is not "too opinion based" unlike some questions that are popular, open, and protected by mods, and yet are 100% opinion based.

Side note: If I wasn't just making a texture for the 3D globe on the easiest to work with projection the answer I would have given is that map that is basically an equirectangular but angles in to account for the east west deformation.